‘However, his statement was extremely powerful in regards to the pressures.

‘We talk about teacher pressure, but headteacher pressure is even bigger.

‘It does come back to funding, having to balance those budgets, having to reduce the staffing.’

She added: ‘I think it’s a sad case and the worst thing is it’s not individualised to this one person.

‘It think it’s the pressure and intensity that he felt.

‘I can’t condone him breaking the law, but the pressure he felt, he’s not alone. People up and down the country will be facing this.’

Staff are facing intense pressure to deliver the curriculum to pupils while facing meaningless targets and competition with business-like academy trusts, she said.

She added: ‘It does mean that in schools with the number of staff you’re dealing with, how do you deliver the curriculum, how do you meet those targets?

‘You then throw in the academy system, which isolates.

‘It’s leaving them more isolated, almost in ivory towers having to make those decisions.’

She said of Portsmouth: ‘It’s a city that’s a tough place to work, it’s really a hard thing.

‘I think the pressures are intense.’

In his mitigation, the headteacher said the Thinking Schools Academy Trust had put him on ‘pre-capability assessment’ as they did not have ‘faith in my ability to lead the school’ and extended that despite him meeting his targets.

Last term the school ran ‘with a quarter of the teachers away on long-term sick leave,’ he added.

Ms Martin said it was ‘up to the government’ as they were putting pressure on schools and local authorities.

She also urged Ofsted to ‘put their money where their mouth is’ by identifying the reasons teachers had a huge workload, and then not just note it but aim to resolve the cause of the problem.

The National Association of Head Teachers only last month published a survey of 800 school leaders, revealing two-thirds said they knew staff were leaving due to workload and wanting a better work-life balance.

Respondents to the survey said there was a ‘rise in the failure’ to recruit senior leaders since 2016.

In a statement released last month, Paul Whiteman, general secretary of NAHT, said: ‘Anyone working in a school knows how rewarding it is to help young people learn and grow.

‘On a good day, there’s no better profession to be in.

‘The trouble is, our teachers work longer hours for less money compared to their peers around the world.

‘Today’s graduates are attracted to other professions, and current teachers are leaving in search of other careers.

‘Budget cuts mean that pay rises and professional training are not keeping pace with teachers’ expectations. They don’t ask for much but they are getting even less.

‘The government must make the changes necessary to ensure a workforce that can deliver the best education for all.

‘This should be the focus of all our attention, to attract and retain teachers, pay them properly, treat them well and respect their need for a proper work-life balance.’

Lib Dem opposition education spokeswoman Councillor Suzy Horton, a former school teacher, said she had seen an increase in teachers with mental health problems.

She added teachers had always worked long hours, but now they were asked to do work with targets that may not benefit pupils.

Cllr Horton said: ‘I don’t think it’s the working hours, I think it’s the nature of what we have to do to satisfy another agenda rather than what you want to do as a teacher.’